Thanks Lord Soth, Lon, Will and Francesco for the flood of useful responses.

I have no experience with cryoed tubes, and therefore don't have an opinion formed on any sonic differences. However, the word from you folks that this a reputable source for a premium matched pair is good enough for me. I guess that the cryo process at least weeds out tubes that may be structurally questionable because I imagine anything kind of frail or questionable wouldn't survive the process.

I'm sure that getting a pair or two from cryoset and just using those in the CSP3 will save money in the long run, as I'm not burning up expensive sets of tubes. So I'll order some up. Thanks again.

Speaking of burning up tubes, sorry didn't get an answer but could my fresh matched pair of 6922's have been damaged? I hope not.

Francesco- I have a French Mazda 5Y3GB that I've been trying in the CSP3 for about a week. It seems to be a very nice tube, can't say for sure yet where it stands sonically but it seems nicely balanced. One thing I can say with certainty is that is a BEAUTIFUL tube. Not a great picture, but just look at that - -

I thought I'd share my experiences with 6922/6DJ8 tubes in my CSP2+. I bought mine used, and it came with a trio of Gold Lion6922's. Bottom line is that they didn't work in the output positionswithout noise, particularly in the right channel. I didn't get any popping sounds, but it was obvious that they weren't the best choice for outputs. I have tried each one in the input position, and they worked fine, so no apparent damage.

I ordered a trio of cryo'ed 7DJ8's and tried them. The right channel was a bit noisy but I went ahead and used them. They were soundingvery good until, after about a half-hour into the session, I noticed thebalance shifting to the left channel. I sent the right channel tube back to be replaced. The seller called me and said that the tube had completely shorted, and it was the only one of that type that he had seen do that. He replaced the tube (NOS) under warranty, but said that he would not do it again due to the circuit being originally designed for a 6N1P.

At present I'm using the cryo'ed 6N1P's from Cryo Parts, which are theexact same tube as the stockers (except, of course, they're cryo'ed),and they are sounding great. I'm done rolling the outputs.

Sooooo, in my experience, the output positions are VERY tough on the tubes. Choose carefully if you decide to roll them.

I'm equally surprised to hear about your experience with the Siemens E288CC.The choice of rectifier might have have something to do with it.I'm using a 5R4GY which is stronger than a 5Y3 but weaker than a 5U4.

Maybe that is the cause?

My E288CC are a strong matched pair producing 30mA readings vs the usual 15mA reading for a typical 6DJ8 tube. (BTW, for any tube newbies reading this , this behavior is expected). I'm getting a louder output from my CSP2+, which is consistent with theory.Maybe it's your tubes?

Or maybe the CSP3 does'nt play nice with the E288CC?( according to Steve , the circuits for the CSP2+ and the CSP3 are supposed to be the same)

Just speculating out loud.

I'll expect to receive my CSP3 before the end of this month so I'll be able to confirm the usage ( or lack thereof) of the E288CC very soon.

Hello peopleI receave the 6N1p-EB from Russia they are beautifull, i put in my CSP2+and no hum no noise, nothing.I will wait a few days for the sound, but i thing tey will be very goodBon week endfrancesco

I tried a Valvo 274B, a Westinghouse labeled RCA 5U4G-ST, a Philips 5R4GYS, a Chatham 5R4WGY, and a Heintz/Kaufman 5Y3WGTA. All no luck with these tubes labeled E288CC and claimed to be Siemens by the seller. They are cool looking tubes...like a 6-type but 1/4 or so taller with the extended area above the getter...gold pins, grey plates, and the hallow getter has two supports, angled a little outward, symmetrical, and passing through a shiny plate that is a bit above the top mica. One getter support has a silver "shield."

They play very quiet at full volume on the Torii with the CSP3 set as usual, but also full on the volume pot. They act similarly in the input position of the Torii. Both channels act the same.

It will be interesting to see if your E288CC work in your coming CSP3. If mine is an accurate example, it is a great sounding pre to me, and good for tube changing, but with the output limited, not totally a tube rollers dream.

I am however getting sound I like quite a bit with some 6BQ7As. I like some 6N1Ps quite a lot in the output, but at this point, using them may lack a bit of character to me, particularly in subtler presentation of spaciousness and micro information. At least at my very green stage of exploration, I prefer the more delicate/complex sound of some European 6BQ7As.

BTW, the Ediswans that did the bad stuff on first try, are fine with a 5R4G or the 5Y3 in...have not checked it with the 5U4 yet. Or it may be to do with the input tube. All a little quirking to me. Oddly, at some times the same tube set with the Brimar 6BQ7As I have can sound noisier than at other times... the outputs appear to be quite touchy electronically.

For experimentation, I did have the CSP3 plugged into my Uberbuss, and that seems to keep a constant 120 volts by my meter. Edit: I tricked myself. Every time I checked the Uber over the last several days, it read 120. I just checked and it read 122.3! So the Uber does not likely control voltage, just happened the grid was consistant (at least at the moments I checked it). So voltage in does appear to be part of the quirkiness I am finding with some 6BQ7As. Then, to play with the voltage, I plugged a Variac into the Uber. Then an Audio Brickwall (modded with a good receptacle and AC plug) into the Variac. And finally the Torii and CSP into the Brickwall. Now I can play with the voltage on both at once. Lowering the voltage a bit so far seems to have some benefit on 6BQ7A noise.

I by no means have a handle on this pre yet. And of course it works flawlessly with 6N1Ps in the output positions. I just love the refinement one can get adjusting the sound with tubes, so I am messing around until I can get a call in with Steve.

It is all too mysterious for me...too close to some edge or edges. I am now back to the GE/RCA 5U4G-ST and the Ediswan 6BQ7As are being very civil, with just a little hum, ear close to the speakers.

My variables I can discern seem to be mostly voltage from the grid as far as I can guess at this point...but I wonder. When I first put in some Brimar 6BQ7As they too were noisy, but not that weird, repeating, building steam to popoff sound. Then they seemed to get better the next AM (perhaps the next AM voltage was lower???). I ran them a while, and all seemed well until late the next night when they got a bit noisy. This is when I thought of playing with the Variac/voltage. But maybe tubes that are close need some time in the circuit for some reason as well.

That said, different rectifier types sure effect the sound a fair bit, so are bound to be effecting the power to the other tubes in some way..voltage or amperage or both. So exploring the different rectifiers may help. I could not get a single 6922 to work in mine when I first tried it, but that was I think with the Valvo 274B in. I will give rectifier changing a try with some poppy tubes later and see.

Maybe Lord Soth (or another member) can educate us on the effects of rectifiers on the circuit???

So I put a barely used, high testing, well matched 67 Mazda/Dario E88CC/6922 in the output. This was with a very nice early 60s Siemens 6DJ8 input, and the 50s GE/RCA 5U4G-ST.

Steady Noise, but not the crazy stuff.

Then I put in some barely used Premium Telefunken PCC88s/7DJ8. The crazy noise stuff.

Then some cryo'd Sylvania 7308s. Similar noise to the Mazdas but a little quieter. I think this is an improvement, but no good. So presumably my voltage reduction is helping.

I left in the above tubes changing the rectifier. An early 50's RCA 5U4GB, Chatham 5R4GWY, RCA 5Y3GT, and Valvo 274B...all having a little different variation on the hum/noise, but noisy none-the-less.

I hope Steve will give some insight, but for now, I am sticking to 6N1Ps and 6BQ7As.

Well we all know that different rectifiers affect the overall sound even though they are used to do one job only and do not carry a musical signal. They supply the rectified ( ac ~ dc ) high voltage rail. I know there are some 600v caps in the circuit which the rectified voltage will pass through to take the rough edges, or ripple, off. The smoothing caps. Of course there will be a tolerance in the circuit where everything works ok even with small % above or below the desired V/A. Why some output tubes aren`t compliant with certain recs can only be down to the tolerance being just to far exceeded for the particular output tube. A mismatch ? The tube data fineprint may hold more answers.Until I read this thread I assumed the 3 signal tubes in/out would all be one type, matched, which is what I use..7dj8 B Boys in the CSP2+. In the ZP3 there is no confusion as the in/out tubes are different. Love reading about the tube rolling. :)

Thanks Marky...I wonder now after my tests if the rectifier has much effect on this issue. Must be pretty much all about how the SRPP is configured. The oddity to me is that if the circuits of the CSP2+ and CSP3 are the same, why are some doing better with the 6922 types as outputs, and others not well at all.

I just had a really good Mazda E88CC/6922 blow in my Torii that was NOS and only used maybe 100 hours by me. This was a few hours in the Torii after trying to use it in the output of the CSP3 for a few minutes, where it worked, but with noise.

Like Funch, I am now worried that this circuit may be dangerous for some tubes. No technical knowledge to indicate this, and it may be a circumstantial quirk, but I am not putting in any more tubes in the outputs other than 6N1P and 6BQ7As until I know better.

The rectifier alters the supplied DC and hence the circuit . The same tube will sound different when supplied with a different current.

My experience with the CSP2+ is that the choice of input tube has a bearing on the final output sound too. Steve mentioned this too in one of his articles.Tube synergy is very important which I found out at great $$$$ .Yeah, tuberolling is expensive but I enjoyed it nonetheless.

I've already have a working set of tubes for my CSP2+ Synergised for my current audio set-up.

I really can't wait to transplant the exact same set of tubes over in my CSP3.

Here's a chart of various rectifiers with their corresponding voltage drops. It is this voltage drop that changes the operating point of the tube. The voltage drop represents the voltage at maximum current draw. You won't actually get a 60-volt drop from a 5Y3 since you are only drawing around 80ma max.